To determine the top left resistor’s value, place the
voltage source on the top of the resistor and the ammeter
going to ground on the bottom. This will insure a one volt
drop across the resistor. Now, place the guard between
the top right resistor and the bottom right resistor; this will
prevent current flow through the center resistor and open
up the single parallel path around the test resistor. The
value of the resistor can be determined by dividing the
voltage by the measured current.

1 volt/ 1 mA = 1,000Ω

Answer 2 (top right resistor)

To determine the top right resistor’s value, place the
voltage source on the top of the resistor and the ammeter
going to ground on the bottom. Now, place the guard
between the top left resistor and the bottom left resistor;
this will open up the single parallel path around the test
resistor. The value of the resistor can be determined by
dividing the voltage by the measured current.

1 volt/ 1.471 mA = 680Ω

Answer 3 (bottom right resistor)

To determine the bottom right resistor’s value, place
the voltage source on the top of the resistor and the
ammeter going to ground on the bottom. Now, place the
guard between the top left resistor and the bottom left
resistor; this will open up the single parallel path around
the test resistor. The value of the resistor can be
determined by dividing the voltage by the measured
current.